I know that the middle seat is supposed to be the safest for car seats. But I've also heard that it may not work depending on how the middle seat is shaped, and also LATCH is usually only on the side seats.
So I'm just curious, where did you install your car seat? Middle or side?

Re: Where to install car seat?
When it was just one we did passenger side, because we were lazy. Knowing what I know now, if I were to do over I would do the middle seat (in our car where that is an option,) even if it meant not using the LATCH. LATCH does not equal safest. W/ the infant carrier & base putting the base in the middle seat using the seatbelt isn't tough.
In my Elantra it had to go on the side. That back seat was just way too small for me to have to climb around to get her in and out - I'd have even more back problems than I do now. But it was a midget car.
She's still on the side in the Rav4, but that's more out of habit. I need to replace her carseat from the accident (we're using the one from my Mom's car right now), and when I do, that may go in the middle.
Someone's getting a little brother!
We had to install both of ours on the passenger side. I drive an '07 Civic and I'm 5'8" (but my height is all in my legs), so the only option for the driver's seat to be where it needs to be for me to comfortably drive is to have it out of the way of the driver's seat. DH is taller than me, and occasionally drives my car, so it would have had to be in that position anyway for him even if I hadn't needed it there. DH's car is an '06 Odyssey w/captain's chairs in the middle row, so we didn't even have a middle seat option in that... and we just randomly chose the passenger's side there; no particular reason.
We do use LATCH in both cars b/c it's there, and it does make installing the infant base REALLY easy. Didn't really make a difference w/the convertible seats, though - those things were a beast to get installed properly.
... every single day of forever.
In our Volvo wagon, we started out putting the car seat in the middle. We have a Britax marathon, and had to lenghten the LATCH straps so that we could use the hooks from the two window seats.
Now that she's 3.5, it is WAY to hard to put her in the middle, so she's on the passenger side.
FYI Most car manufacturers do not endorse the use of the side latch clips for use in the middle seat position. This post by the car seat lady has a good explanation of why and what cars you shouldn't do this in.
https://www.thecarseatlady.com/vehicles/the_latch_system_10.html
I have a Civic and we installed it in the middle. It fits just fine and DH who is 6'1 can slide the seat back to where he normally does. We had ours installed and inspected at the Susquehana Spine Rehab place in Har co..they were super helpful in giving all the info you need and will inspect your install and then will teach you how to do it properly. It was hard to get it so tight it took both me and the car seat person in the car to do it right. They did it for free so that worked for me!
https://www.bnisuccesspartners.com/AboutOurChapter/OurMembers/HarfordCountyChiropractor.aspx